Would it really be possible to interpret it that way if you just said "Yes there is"? Oh well, it just sounds very odd to me. Anyway Jo is unambiguously a positive (contradictory) answer to a negative question in Standard Swedish, so it would not be possible to misunderstand here.

It would sound odd to me too, but "yes there is" as an answer to "Is there no food" would also be odd. I think one would more commonly say either "yes, there is food" or just "there is food" or "no (you're mistaken) there is food." It's hard to answer English questions with negative presuppositions with either just a "yes" or "no" without risk of being misunderstood, so, mostly, in English the answer would be more fully spelled out. But good to know that Swedish has a better solution!

I wonder if "jo" is in Swedish like the word "doch" is in German. In German you can have a short or very long sentence making whatever supposition, usually in the negative, and then just use "doch" to express the contrary. E.g. The children have no food. "Doch" , i.e. they have food. E.g. You don't like it when i have friends over for dinner and we play games. "Doch" = I like all of that.

This reminds me of "si" in French, which is either used to answer positively a negative question, like: "Il n'y a pas de nourriture ? - Si !" ("Is there no food? - Yes!"), or to affirm the contrary to what someone just said, like when children argue: "Non ! - Si !" ("No! - Yes!"), which sound like similar usages to me as a native speaker. Is it the same in Swedish?

When you say "positive contradictory answer" what do you mean? Do you mean when you are answering "yes" to a "no" question -- "aren't you coming? Yes I'm coming." Vs. "Is that a banana? Yes that is a banana"

It is unambiguous because the answer is "Yes, there is.".
If one had stopped at "Yes!", it might mean your assumption that "There is no food" is correct.
Still, the answer "Yes!" to such a question is colloquial and not proper English. The correct answer is either: "No, there is none" or "Yes, there is [some]".
Again, in this case, adding "there is", removes the ambiguity as "there is" means "there is some[thing]" otherwise you have to explicitly add a negative like "none" or "nothing", e.g. "Yes, there is nothing!"

I enjoyed this discussion. As to how it's ambiguous, I remember hearing an old, old (American) song for the first time as a child: "Yes, we have no bananas..." and puzzling over it endlessly. My father used to sing it when he wanted to confound his children, I suppose.

Perhaps its confusion is the implied contradiction when one hasn't learned that positives and negatives can be confusing and that not everything is black or white.

For fun, Wikipedia has the full history (it goes back to the 1920s, a banana trade war) and YouTube has endless versions of the song through the decades since. I enjoyed the stroll down memory lane, thank you. ;-)_

I like the Swedish use of ''jo'' to refute negative statements. It seems it is more complicated to answer a negative in English, and relies on how we emphasize our words. We would much rather answer the question, ''Is there any food?'' If I hear ''Is there no food?'' the speaker suspects there is not, and will follow with ''Why isn't there any?'' or ''Then, go get some!''

I think one would usually ask that way in Swedish too: Finns det någon mat? But we needed some short negative questions, i.e. questions that assume a negative answer, and they aren't that easy to come up with.

I will add that I've seen "jo" as a potential vocabulary word in the Questions Lesson, but never got it in an exercise. I have never seen "det gör det" anywhere until until now. My dictionary helped me with "jo". Now - what is up with "det gör det"? "It [does, makes, causes] it."? Göra seems to be one of those slippery verbs that can have colloquial/figurative meaning. Is there a way for me to think about this verb that will help me understand expressions like "det gör det"?

I think I get it. This reminds me of a more formal/slightly archaic mode of affirmation in English (using your examples):

Har du sett henne? - Ja det har jag.

Have you seen her? - Yes I have.

One could also reply, "Yes, that I have."

Talar hon svenska? - Ja det gör hon.

Does she speak Swedish? - Yes she does.

Yes, that she does.

When I learned French, I came to realize that we who speak American English have dropped many words that "flesh out" entire grammatical constructions. When I looked backwards to an earlier form of the language (specifically Dickens, who never missed an opportunity to use MORE words!), I discovered the missing pieces. Looks like I've fallen victim to the same phenomenon. Guess I'll have to put the Victorian English part of my brain back to work again. Oh no...........

"Does there exist any food? No, there does not!"
The gör is like does.
Also, är only translates to is for some meanings. Finns is like exists. In English, "Yes, there is!" means "Yes, it exists!" however, "Yes, it is!" means something completly different. Those two uses of is have two different Swedish translations.

Thank you for the interesting link! It's very strange that it was the answers to negative questions (which are less frequent, at least today) that won out.
As for jo, both German and French have special words for this, so it's not a rare phenomenon in European languages.

Finns det ingen mat? is a negative question, which sort of presupposes that there is no food. Is there any food? is an open question about whether or not there is any food, and in Swedish it would be Finns det någon mat?

Yes, that does help a little. I didn't remember that 'det' could also mean 'that'. It's still a little confusing when translating it literally, but that makes a bit more sense now. "Yes, that it does" just seems strange when I expect "Yes, there is".

Is there any native Spanish speaker here? For me it sounds like the (maybe incorrect) Spanish custom to say : 'no, si ' together , i.e. "¿No hay comida? - No, si hay. (Isn't there any food? No, yes there is. "With NO expressing that the assumption is incorrect and SI saying there is. So 'no si' = jo.

You can use both, but in normal speech you tend to use the short version. Even if in this particular example it isn't shorter.
On a statement the verb always goes on the second place. "Jo" is not part of the statement.

Hi there, I just wanted to mention how difficult it is to learn this concept since each time this structure appears in testing, it is always in this format. Since the answer is the same each time, it becomes more answer memory than actually helping us to learn this in a way that will help us use this. It would be very helpful if the phrases could be included in translation exercises (particularly in the english to swedish) rather than simply the drop-down with "jo" as the answer.

Because here it doesn't work with nej.
You can say the Swedish version of "Yes, it does" or "No, it does not", but you can't say "No, it does" because that's what jo is for. If you saw inte in the answer, you would know they were using nej.

Actually, they consistently don't accept that type of reordering of the sentence in this course. Your version is a statement that is forced to be a question by using the punctuation at the end, while the exercise is a natural question. You can do the same thing with punctuation in Swedish but they only allow translating like-for-like in these cases.

The question is confusing in any language because you haven't given any more information than the simple is there no food? You have two possible yes answers and one no. Which one do you choose? It's an example of trying to be clever for the sake of being clever but you end up looking the fool for it. It's basically a lucky dip question, which would only be acceptable in a contest where you might win a prize, but not in a language course.

Because we have no idea if there is any food. There are two possible answers, but in order to answer the question you need to provide more information. It's just a lucky guess question. You've got a fifty/fifty chance of getting it right or wrong. If you're trying to differentiate between ja and jo there are better ways to show people, this is just a bad way to do it.

Maybe but there is still a better way to illustrate that point instead of an ambiguous question. In English, to say, is there no food? could have one of two answers, you're asking a question. is there any food? Same again, you need more information. My first example has a negative tone, the second is more neutral but I'm still confusing the reader because they don't know if there is any food. There is no equivalent in English because yes means yes, the only difference would be in emphasis on the word yes, a firm yes is positive but a tentative yes might suggestive uncertainty. The only thing I could suggest is the answer is redone. For example. Is there no food? Yes of course there is food, add something to make it look as if there is food. Google has several words, like självklart, givetvis, naturligtvis. It changes the answer and at least suggests there is food, you can add the jo as well just to show the difference.